The activity of lemon butterfly P. demoleus on bael plant, noticed from first fortnight of July and was found maximum (6.6/10 shoots) in first fortnight of September. The caterpillar population started decline in second fortnight of September (5.45/10 shoots) which continued up to second fortnight of December and completely disappeared in first fortnight of January. The leaf damage varied from 1.60 to 14.20 per cent in different months and maximum infestation (14.20%) was observed at first fortnight of September, 2016 and after that started decreasing to second fortnight of December. The lemon butterfly exhibited significant and positive correlation with morning relative humidity (r=0. 595) while maximum temperature (r=0.345), minimum temperature(r=0.271), evening relative humidity (r=0.094) and rainfall (r=0.033) had shown a non significant positive correlation. Correlation between damaged leaves and weather parameters on bael exhibited significant positive correlation (r=0.559) with the morning relative humidity and non significant positive correlation with maximum temperature (r=0.325) , minimum temperature(r=0.267), evening relative humidity (r=0.129), and rainfall (r=0.021).